Ambrosia artemisiifolia, with the common names common ragweed, annual ragweed, and low ragweed, is a species of the genus Ambrosia native to regions of the Americas.
Taxonomy
The species name, artemisiifolia, is given because the leaves were thought to bear a resemblance to the leaves of Artemisia, the true wormwoods.
It has also been called the common names: American wormwood, bitterweed, blackweed, carrot weed, hay fever weed, Roman wormwood, short ragweed, stammerwort, stickweed, tassel weed.
Distribution
The plant is native to: North America across Canada, the eastern and central United States, the Great Plains, and in Alaska; the Caribbean on Cuba, Hispaniola, and Jamaica; and South America in the southern bioregion (Argentina, Chile, Paraguay, Uruguay), the western bioregion (Bolivia, Peru), and Brazil. The distribution of common ragweed in Europe is expected to expand northwards in the future due to climate change.
It is the most widespread species of the genus in North America, to which most of the other species of Ambrosia are endemic. During the summer it causes allergic reaction in those who are susceptible.
Description
Ambrosia artemisiifolia is an annual plant that emerges in late spring. It propagates by seed.
It is much-branched, and grows up to 70 centimetres (2.3 ft) in height. The pinnately divided soft and hairy leaves are 3–12 centimetres (1.2–4.7 in) long.
Its bloom period is July to October in North America. Its pollen is wind-dispersed, and can be a strong allergen to people with hay fever.
It produces 2–4 mm obconic green to brown fruit. It sets seed in later summer or autumn. Since the seeds persist into winter and are numerous and rich in oil, they are relished by songbirds and upland game birds.
This species is host to the following insect-induced galls:
Aceria ambrosiae Wilson, 1959 midge that forms bud-galls
Asphondylia ambrosiae Gagné, 1975
Aulacidea ambrosiaecola Ragweed stem gall...
